Dynamics of Starch Degradation and Expression of Related Genes During Chilling Stress in Grapevine

Frost in late spring is one form of environmental stress that severely damages grapevines. Starch is a major product of photosynthesis that plays essential roles in many biological processes in plants. The dynamics of starch metabolism and related gene expression in the leaves of grapevine during chilling stress have remained unclear. Here, starch metabolism in the leaves of Vitis vinifera cv. Cabernet Sauvignon was characterized under normal (25℃) and late-spring frost mimic (4℃) conditions. The results from anthracenone colorimetry, iodine staining and ultrathin sectioning are consistent with a low temperature during the night inhibiting the degradation of starch. Four α-amylases ( AMY ) and ten β-amylases ( BAM ) genes were identified in the V. vinifera genome (PN40024). Low nighttime temperatures downregulated the expression of genes that encode amylases relative to optimal nighttime temperatures. The expression of other genes with functions related to starch degradation, such as like starch excess four 1 ( LSF1 ) and isoamylase 3 ( ISA3 ), was induced by low temperature. The glucose, sucrose, maltose, and fructose contents increased in plants grown under low-temperature conditions with less consumption of starch, indicating complex regulation of soluble sugars. The findings here provide clues that will lead to enhanced frost tolerance of grapevine leaves by modifying the starch degradation pathway.